In its broadest sense, a floor is comprised of a subfloor over which a decorative covering is installed. Typically, the subfloor is either a slab of concrete or one or more sheets of plywood supported by a combination of joists, beams, posts and, in multiple-story buildings, bearing walls. The primary types of floor coverings used in structures are “soft” floor coverings and “hard” floor coverings. As its name suggests, soft floor coverings are soft, quiet underfoot, and tend to yield upon application of a force thereto. Hard floor coverings, on the other hand, are hard and rigid, but tend to be durable and easy to maintain.
Generally, an underlayment is installed between the subfloor and the floor covering. The underlayment provides a cushion and decreases the wear of the floor covering. Underlayment also smoothes imperfections in the subfloor. Cushioning is important for both hard floor coverings and soft floor coverings, although the type of underlayment varies for each application. Hard floor coverings, such as wood, tend to have thinner, denser underlayments that absorb the sound of a person walking on the hard floor coverings. Soft floor coverings, such as carpet, tend to have thicker, less dense underlayment to enhance the softness of the soft flooring product, reduce wear, improve cleaning, and reduce high points or “peaks”, low points or “valleys”, and other irregularities in the subfloor. Underlayments may also provide a more level surface for floor coverings.
Underlayments are made out of various different types of materials. Some underlayments are made out of nonwoven fiber batts. Other underlayments are made out of foam coated onto a woven or nonwoven fabric scrim or substrate. Foam rubber or latex can also be used as underlayment. Additionally, underlayment can be composed of prime polyurethane foam, which is cut to various thicknesses from larger foam blocks. These prime polyurethane blocks do not incorporate the use of ground, recycled scrap polyurethane into the process, as in bonded foam. Prime foam is produced by mixing various chemical compounds together to create highly cross-linked polyurethane chains where density is primarily controlled by the amount of water in the formulation, and to a lesser extent, the degree of off-gassing resulting from the reaction of water and isocyanate, which influences the degree of cell expansion.
Perhaps the most common type of underlayment is bonded foam underlayment. Bonded foam underlayment is manufactured by shredding scrap foam into small pieces and then forming a larger piece of bonded foam from the shredded pieces of scrap foam. In one method, after the scrap foam is shredded, the foam pieces are coated with a pre-polymer comprised of isocyanate and polyol, and compressed into a foam log. Moisture, usually steam, is then added to the foam log to cure the pre-polymer, thereby binding the foam pieces together.
One of the ongoing concerns of many bonded foam underlayment manufacturers is the need to reduce manufacturing costs. Lowered manufacturing costs result in lower product costs, which make the bonded foam underlayment more appealing to the consumers. Bonded foam underlayment consumers, particularly large retail outlets and flooring installers, are constantly seeking the lowest price on flooring underlayment and frequently change suppliers in order to save a few cents per square foot of underlayment. Thus, it is in the manufacturers' best interest to produce flooring underlayment for the lowest possible price. As the cost of upgrading manufacturing equipment to improve efficiency can be prohibitive, most manufacturers seek to lower production costs by using less expensive materials to manufacture the underlayment.
Another ongoing concern regarding bonded foam operations is the byproducts produced when mixing and curing the pre-polymer. Traditional bonded foam pre-polymers and their chemical precursors generate numerous volatile organic compounds (VOCs) as a result of raw material chemical vapors or the reaction between the isocyanate and the polyol. VOC emissions are closely monitored and regulated by the Environmental Protection Agency (EPA) and other environmental groups and in many cases there are limits on the amount of VOCs that a manufacturing facility can emit. Thus, any process or product that reduces the VOC emissions is preferable because it is more environmentally friendly than the current bonded foam processes. In addition to the environmentally beneficial aspects, a sufficient reduction in VOCs allows manufacturers to market their products as “green”, which is a product trait preferred by many consumers.
Consequently, there exists a need for a flooring underlayment that is less expensive to manufacture than existing flooring underlayments, which will allow manufacturers to produce and sell a flooring underlayment to consumers at a reduced cost. A need also exists for a method for reducing the VOC emissions associated with a bonded foam production process. A new method for manufacturing bonded foam product has now been found which employs vegetable oil polyol. The process and resulting product provide a lower cost, higher quality product and the manufacturing process reduces VOC emissions.